Copolymers of a polyene, an alkene, and an olefinically unsaturated aromatic hydrocarbon



Patented Sept. 2, 1952 COPOLYMERS OF- A POL'YENEQAN ALKENE,

" AND AN OLEFINICALLY UNSATURATED l =AROMATIGHYDROCARBON a 1 ,William,J. Sparks, Westfield, and David Youn'gRosella'N. J assignors to StandardOil Development Company, a corporation of Dela- No Drawing, ApplicationMarch 21, 1046, Serial No. 656,148

r "12 Claims.

This inventio'ii' relates to novel high mole ular weight polymericchemical products anclto -'Inethods of 'makingeame. ,More particularly,it 'relates'to" the preparation of copolymers consistinga'lmo'stf'entirely of aliphatic constituents but contaming'afveryifsmall amount of a com- *bined" cyclivmdclif yingconstituent.The invennon m y-bfe typified a by a copolyrher of 97%'offisobutylenejand 3% of styrene. l

Us-S. Patents" 2,215,423 anaazmmie ldisclo'se copolmersofiscbutylene andsty ene in ageneral' way; anddescribe methods of effecting thecopolymerization, i. e. attempera ture's below -0"C.,"e. g.' I0"C.,, 400., 80 70., 'or lower,

and byfthe .use or" "an active" halide, polymerization catalystq These,patents disclose that the proportions of thetwofreactants may be variedin "order j to produce thermoplastic copolymers "having the desiredrhardness', melting point,

s c utyeine; m y'f' ange from 1 to 90%.

Howeverjjit isfdifficul-t or impossible to prepare fsuchpcpolymersinavery high molecular weight range seen-as *50L000, 100,000 or above, and

fanother difiiculty i's'that wheniany such copoly'rneishatingmolecularweights even as low as lOZQOQare dissolved in parafiiniclubricating oils they tend --to come sut of j solution when cbble'ddownf-to temperatures of "about 50 F. or newer. {Furthermore althoughwhen compounded; with natural or synthetic rubber, suchco-polmnersgreatly improve the workability therefgthey genera effectaslight reduction either Q in-elongation. It 's aise hat isobutylenealone can be pe i'r zeriited}to polymers ranging from viscous stickyfiuitls hating a molecular weight range of 1,000 to 10,000 or 15,000, onup through "a "tacky -p1astic stage, to dry "substantially 'nontaw'yrubbery po e'rs' having molecular weights n1 j1=50000 and even inuch"higher. However, suchi-p'olybi'itenesgpaiticulai'ly those of"very highmolecular wei'ght'sgiio not have as good stability tofsiurilightan'dultraviolet-light as might be desired, and deInothaVe entirelysatisfactory stability: against 3. thermal or -mechanical molecularweight breakdown.

-It 'has' now-been ioundthat between the pure polybut'enes and thestyrene-i sobutylene copolyiiiers hai ing '5 car-hr more per cent ofcoinbined-"styrene, it is possible to make novel bopol ymer's having 1novel and unexpected characteris'tics hot possessed by either of the twopreviously kirewn types of polymeric materials. Thu'sy itl i's foundtnatwhen-about 0:5 p

about 4 oi' i.5"% or so "o'fstyrene' i's' 'cepbiymer zeu withisobutylene, the"resultantgijcopolyme surprisingly better thermalfstabilityftha butene, and it is believed -th tthe-smau a aunt ofstyrene 'coihb'inedinthecopolymer molecule acts somewhat like "an"anti-oxidant in" prevent: ing depolymerization or molecular'weight"bie'akdown at elevated temperaturafwhich' ifs'thou'ght to be atleast partly "dueto or at least accelerated by incipient ozdda'tion,becauseknown oxidation inhibitors such as certain alkyl Iphenolstendv-toreduce the thermal decompositiono'fhigh molecular weight polybutenes.

These new copolymers may be milled into natural rubber or syntheticrubbers such as G RS (butadiene-si', 5 rene) "Gl t- A (butadieneacrylonitrile) and C R;{Kisobutyleneflsoprene copolymer of lowunsaturation), as wellaspther types such as neoprene, and organic polysulhderubbers, at hot mill temperatures; such. as; i50- 330, F, with lessundesirable breakdown-than can poiybutene of similar molecular weight. I

, These new copolymers having less than-5% of combined styrene 011equivalent cyclic constituent, may be made in a wide range of molecularWeights, according to the temperature of copolymerization used and theparticular type of catalyst used. However, the invention is applied toparticular advantages by effecting the .copolymerization attenipeifatures below 50C. so the resulting ccpolymerwwillhave -amclecstyrene and 5 of isobut'ylehe is cOpolymeriZed "at"10-3-. C:. i-n methylchloride ;-sc1utien =and using as catalyst a solution of "aluminumchiefride'dissolved in methyl'chloride,'-the resulting copolymer willhave a molecular eiEht-oflabout 25,000, and if theproportiohiofreactants is'reversed so as to-use"60%' of styrenefin'thefee'd, the copoly-mer will have only1-8-000 to 20,000

mol. wt., whereas under-similarcbpoly'm'eriaation conditions copolyr'ner's having less than 5%;61 combined styrene ate made haf n'gjuiolecular weightsranging'iroin about 70,000 11 1p to 200;0'00. Thesenew copolymers whenlmad einfthef very high molecular weight range "suchas 150,000

to 200,000 or higher are dry; rubbery i ducts having no cold flow. IThey resemble polybuterie in general physical texture anglpppearancefexcent-that for any particular mol'eculauweight they have a physicaltexture corresponding more closely to a polybutene having a molecularweight about 25% higher.

Another remarkable characteristic of these new copolymers -is that theyhave quite gradual heat-softening characteristics much more resemblingpure polybutene than the more sharply thermoplastic type ofheat-softening properties of styrene-isobutylene copolymers havinglarger amounts of combined styrene.

The copolymers of this invention also have an unexpectedly goodcombination of good solubility in paraffinic lubricating oils even atvery low temperatures, e. g. R, and good stability under shear tests. Anindication that the combined styrene content of these new copolymers iscritically important even though small in quantity, is that thesecopolymers are found to dissolve in benzene to form a clear solution atC. whereas polybutenes of similar molecular weight do not. Anothercharacteristic which may be particularly valuable undercertaincircumstances, is that the copolymers' of this inventiongenerally have a much narrower molecular weight spread than isobutylenepolymers made under similar'polymerization conditions of temperature,type of catalyst and solvent.

In carrying out the copolymerization, the catalyst to be used may bealuminum chloride, boron fluoride, or activated boron fluoridecontaining 0.1% of ethentitanium tetrachloride, aluminum alkoxide--aluminum chloride complex (AlC13.Al 002mm 'AlBrs, AlBr3.A1(OC2Hs) s,(AlBra)4.AlOBr and the like. If desired, such catalyst may be dissolvedin a solvent such as carbon disulflde, a low molecular weightsulfur-free saturated hydrocarbon,

a lower alkyl halide, e. g. methyl chloride or ethyl chloride oramix'ture of methyl chloride with AlBr3.Br4.CSz, BFs-isopropyl alcoholcomplex,

BF: solution in ethylene, activated BFs catalyst in ethylene solution.

The'copolymerization is preferably carried out in the presence ofavolatile solvent or diluent or refrigerant, such as propane; ethane,ethylene,

methyl chloride, carbon dioxide (liquid or solid), etc.; such materialsmay be used either as internalrefrigerants or external refrigerants orboth, to remove the liberated heat of polymerization. One advantage ofthe present invention is that due to the use of less than 5% of styrenor equivalent cyclic constituent, both the feed materials and resultingcopolymers are sumciently soluble in lower aliphatic hydrocarbonsolvents such as propane, that it is not necessary to use a lower alkylhalide solvent such as methyl chloride as is required forcopolymerizations involving higher amounts of styrene reaction.

After completion of the copolymerization, re-

sidual catalyst may be hydrolyzed by adding an alcohol, for example,isopropyl alcohol or ethyl alcohol, or water or both,.and removed bywashing the product with water and preferably also with dilute aqueouscaustic soda. Any residual solvents or wash water or other hydrolyzing 4agents may be removed by heating the copolymer with or without milling,kneading or other agitation.

Instead of isobutylene as the alkene, other lower aliphatic olefins maybe used, preferably iso-olefins having =1 to 8 carbon atoms such asisopentene (methyl-2 butene-l), or a normal pentene obtained bydehydration of secondary amyl alcohol, although other lower olefins suchas propylene may also be used.

Instead of styrene as the polymerizable olefinic cyclic compound, othermaterials may be used such as alpha-methyl styrene, para-methyl styrene,alpha-para-dimethyl styrene, dihydronaphthalene, indenes, etc. Variousderivatives or homologues of such compounds having one or more shortalkyl groups (e. g. 1 to 10 carbon atoms) attached to the cyclic nucleusand not interfering with the polymerization, may be used.

A further modification of the invention, as already disclosed inapplication Serial No. 550,488 filed August 21, 1944, now abandoned, ofwhich the present application is a continuation-in-part, is the use of asmall amount of a third reactant,

- namely, a diolefin or other polyene having 4 to 15 carbon atoms. Assuch constituent, it is preferred to use isoprene, although others maybe used such as butadiene; 2,3-dimethyl butadiene 1-3; 1,4-dimethylbutadiene 1,3; piperylene; cyclopentadiene; myrcene; Z-methyl B-ethylbutadiene; hexatriene; Z-methyl-pentadiene; and alloocimene. Also, vinylacetylene may be used instead of such pol'yenes.

The proportions to be used in making up the copolymerization feed stockmay vary somewhat according to the intended purpose. For instance if asaturated copclymer is desired, 1. e. having less than about 0.1 iodinenumber and being substantially free from tendencies to absorb oxygen andharden due to aliphatic unsaturation, then no polyene is used in thefeed, and the polymerizablev mono-olefinic hydrocarbon containing acyclic nucleus, e. g. styrene or equivalent material, should be used ina concentration of at 1 least 0.01% but less than 5% by weight,preferably about 0.5 to 4.5% and better still for most purposes about1.0 to 4.0%. If no polyene is used then the aliphatic olefin such asisobutylene will constitute the remainder of the active copolymerizationfeed, and it will be present in a concentration greater than and may beas great as 99.99%. It is found that even relatively minute amounts,much less than 1%, of styrene, when copolymerized with isobutylene, havea very beneficial effect in stabilizing the polybutene chain againstdepolymerization ,due to sunlight, ultraviolet light, heat andoxidation. 4 n

If a polyene is used such as isoprene,the amount thereof to beusedwill-depend primarily upon the desired amount'of unsaturation in thefinished copclymer, and this should correspond to iodine number lessthan about 50 and should preferably be about 1 to 20, thereforerequiring generally at least 0.1% but not more than 15%, preferablyabout 0.5 to 10% of polyene, although in some cases amounts as small as0.1% may suifice. Also, when a polyene is used, the amount of styrene orequivalent polymerizable cyclic material used may be slightly higherthan when no polyene is used; for instance in such tripolymers theproportion of cyclic material may be about 0.01 to 10%, preferably about1 to 5%, and of course if a polyene is used the amount of allphaticolefin, e. g. isobutylene, will be somewhat less than =otherwise,namely,will be about 70.170 .-99%;p1ieferably about 85 to.95%.

The preferred procedure foncarrying out the copolymerization of thisinvention is to mix the isobutylene-and .styrene, together with the iso-.prene if anyis used, or their equivalents, cool them down to thedesiredoperating temperature by either external or internalrefrigeration, preferably having some diluentor solvent present, forinstance in a proportion of about 1 to volumes .of solvent per volume ofmixed copolymerization feed, and ,then addingto that reaction mixturethe desired amount ofv catalyst or solution thereof, preferablyagitating the mix .ture well during the addition of the catalyst.

After hydrolysis and :removal of catalyst as previouslyqmentioned, theresultant. high molecular weight copolymer may beheated :if desired,with or without milling or other agitation, to remove residual traces ofsolvent, diluent or refrigerant or of water or alcohol left from thewashing step.

The copolymer per se is a plastic, andinmost case rubbery and elastic,solid having an. average molecular weight above 30,000, and preferablyabove 50,000. Molecular weights Well above 300,000 have been obtained.Copolymershaving a molecular weight below 50,000 generally are somewhattacky, while those in the vicinity of 100,000 mol. wt. are only veryslightly tacky and those in the vicinity of 150,000 or"200,000are dryand free from cold flow.

Tripolymers made according tothis invention and having an iodinenumberranging from about 0.1 up to about 50, preferably about 0.5 to 20,are vulcanizable and may be cured by treatments similar to those usedfor vulcanizing a synthetic rubber made by low temperaturecopolymerization of isobutylene in the presence of a small amount of apolyene of 4 to 12-carbon atoms, e. g. l to 3% of. isoprene or 5 to orso of butadiene.

For curing the tripolymer as more specifically disclosed in applicationSerial No. 632,102 filed November 30, 1945, now abandoned, of which thepresent application is also a continuationin-part, one may use sulfurand one of the various fast accelerators or ultra-accelerators such astetramethyl thiuram disulfide, mercaptobenzothiazole, dinitrosobenzene,quinone .dioxime with an oxidizing agent such as lead peroxide or leadoxide or benzoylperoxide, or esters and salts of quinone dioxime, ascuring agents. The quantities may vary from 0.3 to 6 parts by weight ofresin, the 6 parts being used in the case of the esters and 0.3 forquinone dioxime or para dinitrosobenzene. Temperatures, of ouring may befrom room temperatureto 500 F. Time of cure may vary from 10 seconds (athigh temperature) to possibly several daysora week at room temperature.

The isobutylene-styrene type copolymer even without any polyene, "can becured throughthe presence of the benzene ringby reagents such asformaldehyde, or acetyl ,peroxide, heptoyl peroxide, etc.

The two-component copolymers, not containing any polyene, are claimed inco-pending application Serial No. 176,256, filed July. 27, 1950.

The tripolymers of this invention are particularly valuable for thepreparation of so-called pure gum. stocks or white or light coloredsynthetic rubber stocks, because the presence of the small proportion ofcombined styrene greatly stabilizes the tripolymer against deteriorationi molten p'arafiinwax in all proportions, and there due :to :asunlight;--and-/.or..'l1eat, -.-.against "which stabilization. has oftenheretofore :been obtained :byzcom'pounding a large amount .of .carbonblack into-thestockbeforecuring.

Thecopolymersofthis invention may .be used forra widevariety of purposesin-addition to those mentioned above. -.-For instance they may be usedfor coating metal, wood; paper; cloth, glass, and for laminating variousthin flexible sheet material such aspaper cloth, metal foil, re-

generated ;cellulose, cellulose :acetate etc, and

.for- .such purposes the -copolymers. may be dissolved in :-'a volatilesolvent such as naphtha,

.and applied by --vario.us .Lconventional -methods such; as dipping,:spraying,;-roll. coating, .etc., f 01- lowed; by.- evaporation of the.solvent, or the cob lymers .may .be .acompounded ,zwith softening orplastici'zingmaterials :such as mineral ,oils, waxes,.;e. 1g; parafiinwax. orpetrolatum, asphalt or thermoplastic compatible .resinspreferably :of the .hydrocarbon type,..'and when jthus. softened orplasticized, may be used in molten or .heat softened conditioniforianyofthe purposes above mentioned.

These products also a-re particularly well adapted for electricalinsulation; purposes, partlcularly'for dielectric medium,=alone ortogether with paraflin wax, in electrical condensers.

These products may also-be compounded with other types of high molecularweight polymeric materials, preferably those I of a predominatelyaliphaticnature such as polybutene, polyethylene and other polymerizedolefins, aswell as syntheticrubber'of the GR-QI type, -e.- g. made bylow" temperature Friedel-Cra-fts polymerization ofisobutylenewithabout'l 'to-3% of-isoprene, although they'may' also becompounded with naturalrubber-a-ndother types of synthetic rubber suchas those made 'by emulsion polymerization of 'butadiene alone-or intogether with a minor proportion of styrene or 'acrylonitrile.

The copolymers -of this invention, whether made with polyene or not, aremiscible with in differ greatly from styrene-isobutylene copolymershaving z'i' hig-her styrene content, e. g. '10 to or-so.

These copolymers having less than 5% of styrene-or other cyclicconstituent can also be used as viscosity index improvers in lubricatingoils, diesel'fuels or even gasoline.

Another valuable characteristic of this invention is that ,these newcopolymers lend themselves very peculiarly to the formation of many newchemical derivatives because the very small proportion ofstyrene orother cyclic constituent :combined into the copolymer makes theseproducts/susceptible to reaction with strong acids suchxas. sulfuricacid, nitric acid, as well as to other chemical agents such ashalogenation, oxidation, sulfurization, treatment with phosphorussulfides,. e. -1g.. Pass, :alkylation, e.. g. with amyl chloride,acylatione. g. by acetyl chloride, sebacyl chloride, phthalyl chloride,as well as other interlinking resinifying agents, e. "g. formaldehyde,ethylene dichloride, chlorinated paraffin wax, etc.

.The invention willbezbetter understood from a consideration of thefollowing experimental data.

EXAMPLE 1 vA.copolymerization feedwas formulated from 97% by weight ofisobutylene and 3% of styrene. To this mixed feed, powdered solid carbondioxide was added to cool the mixture to -78 C.

and then boron fluoride gas was bubbled slowly into the mixture withstirring. Copolymer formed at a very rapid rate. "The product had amolecular weight of about 33,000 and the yield was about 47%. Thecopolymer was soluble in benzene at temperatures as low as 20 0.,whereas polybutene of the same molecular weight came out of solution at20 C.

EXAMPLE 2 A copolymerization feed was formulated from 95% by weight ofisobutylene, 3% of styrene and 2% of 1,3-butadiene. About 3 volumes ofliquid ethane were added, to serve both as internal refrigerant and asdiluent. When the mixture'was cold, about -90 0., BF: gas was added ascatalyst. The copolymerization reaction was rather slow and resulted ina copolymer of relatively low molecular weight, e. g. about 18,000. Thiscopolymer was soluble in benzene at +20 C. It had an iodine number ofabout 1. 3 I

EXAMPLE 3 Four tests were made to compare the efiect of a small amount(e. g. 5%) of styrene on the curing properties of a GR-I type ofsynthetic rubber made by copolymerizing 97% by weight of isobutylenewith 3% by weight of a diolefin. In the first two tests, the diolefinused was 2.3- climethyl butadiene-1,3 and the catalyst was BFa, and inthe third and fourth tests, the diolefin used was isoprene and thecatalyst was TiCh. In all four tests ethylene was used as refrigerant,the volume ratio of ethylene per volume of polymerization feed beingindicated in the following table, together with the mol per centunsaturation and the Staudinger mol. wt. of the resulting copolymers,and the physical tests including tensile strength, modulus andelongation, on the copolymers after vulcanization for 20 and 40 mins.respectively at 307 F., when compounded with 50 parts by weight of Cabot#9 carbon black, per 100 parts by weight of copolymer, using 2% byweight of sulfur and 1% by weight of Tuads (tetramethyl thiuramdisulfide) and /2% Captax (mercapto-benzothiazole) as vulcanizationaccelerator.

the presence of 3 volumes of methyl chloride as solvent per volume ofpolymerizable feed, and using as catalyst A1C13 in'meth'yl chloride (0.6g./l00 ml). The resulting copolymer had an average mol. wt. of about100,000, by Staudinger method, and was a substantially tack-free,flexible, substantially colorless rubbery solid. 20 parts by weight ofthis copolymer were compounded with 80 parts by weight of natural rubbersmoked sheet and other compounding and curing ingredients as listed herebelow and then cured at 285-287" F. For comparison a compositionidentical except for the omission of the isobutylenestyrene copolymer,was similarly compounded and cured. The abrasion resistance andflexresistance of the resulting products after curing for variousperiods from 5 mins. to 20 mins. are also shown here below.

Table II Recipe No IO ppe NWO Abrasion Resistance (ASTM D39l-40) Mins.cure at 285-287 F;

Flex Resistance to #10 cracking (modii. of ASTM D8l3-44T) Mins. cute at285 F.:

6 175, one 400, 000 100, 000

1 A mixture of about 05% of a complex diaryl amine ketone aldehydereaction product with about 35% of NNdiphenyl p-phenyleno diamine.

1 mercapto-benzotbiazole.

3 isobutylene-styrene copolymer of 100,000 mol. wt. and containing 2%combined styrene.

'The above data show that the incorporation Table I Parts Cabot #9 Curesat 307 F.

Vol Moi. Test v Stand.

011 Additives Catalyst Percent 20 111111. 40 min. Ratio Unsat '1. Mod.Elong. '1. Mod. Elong 1. 411 BFa. 68, 000 3, 130 250 900 3, 260 380 8302. 4/1 5% Styrene... BFa 1. 8 56,000 2, 650 290 900 2,870 440 900 3. r3/1 'liCh 2.0 62. 000 2, 970 480 780 2, 960 740 670 4. 3/1 5% StyreneTic 2. 0 43, 000 2, 880 505 850 2, 970 810 720 of 20% of the 2% styrenetype copolymer of isobutylene and styrene efiected a slight increase inthe abrasion resistance of the compounded cured rubber, and efiected atremendous improvement in its flex resistance.

EXAMPLE 5 Styrene is soluble in a mixture of 1 volume of isobutylene and3 volumes of liquid ethane, to the extent of about 3% by weight. Aseries of tests were made in which a mixture of 2.5% by weight ofstyrene and 97.5% by weight of isobutylene was copolymerized in thepresence of copolymerized at a temperature of 10l C. in 3 volumes ofliquid ethane per volume of liquid copolymerization feed, using gaseousBF'a-as cata lyst, either alone or together with 0.1% Of ether (diethylether) as accelerator. The molecular weights of the resulting copolymersare shown in the following table:

Table III Test No. Accelerator gg Nrm 10, 680 None 13, 350

The above Table lfi shows that' whengasous boron fluoride alone is usedas catalyst for copoly merizing iso-butylenecontaining about 2.5 byweight of styrene, the resulting copolymer has a molecular weight onlyabout10,000'to 15000,

whereas when the BF} is supplemented by-the use of 0.1% of .etherasaccelerator, the molecular weight of the resulting copolymerranges=iromabout 35,000 .to 50.000, This isasurprlsi-ngly good result consideringthat the copolymerization was carried out in thepresence of only ahydrocarbon material, namely ethane, as solvent and refrigerant, becausestyrenehas such alow solubility inv aliphatic hydrocarbons :at low-'temperature that generally a 'halogenatedzhydrocar bon liquid such asmethylchloride' has been used heretofore in copolymerizingstyrene-isobutylene mixtures containinghigher anioun'tsof "styrene,- e.g, 20 to 60% or-so. V l t Another 'series'of tests was mad'eto determinethe optimum amounts of BFs catalyst and'butane diluent, forcopolymerizing 1% by weight of styrene with 99% of isobutylene using0.01% of ethyl ether to activate "the BF3 catalyst 'and using:

solidified carbon dioxide as internal refrigerant, which thereforemaintains a copolymerization temperature of about -78 C. The conditionsof polymerization used in each test, and the molecular weight of theresulting copolymer are given in the following Table IV.

Table IV [Solid CO2 refrigerant-0.1% ethyl ether added to olefinteed-.-- Active" feed-99% isobuty1ene-1% styrene] Percent 13 F3 CatalystPercent Butane Staudlnger Diluent NH, termg oooo oocc wwmCIJNCDHHHHHb-The above data in- Table IV showsthatzwhen 0.1% ether activator is used,copolymers'ranging from 75,000 to about 95,000 mol. wt. are obtainedwith 1 to 3% of BF3 catalyst and without any butane diluent, butcopolymers'having "higher molecular weights in the ran e-oi "100,000'to'130,000 are obtained with: similar-"concentrations 5 ample, 6 in regarto the copolymeriz 'butylene using ethane re of BFs but with 10 to"-%-by weight of butane u Another series of tests "simmered;those-m13 7 ionof 1%" of styrene' with 99% ofis'o'biitylene, wasma e to" determine theoptimum am'oun of ether activatorfo'r 'th'e BFcata1jyst: These" estsoutusing ethan'e' aslrefri I material such as butane as diluent; ethaneas'an internal refrigerant ni f copolymerization temperature" of "about89" C. The various proportions of ether activator used, ranging from 0to 0.4% by weight based on the weight ofpolymerization feed, and theamounts ofBFs" used ranging from 1 to 3%, and the molecula'r'weights ofthe resulting copolymers are-shown in the'followingtable: Table V[Polymerization of'99% is0buty1ene1% styrene feed with BF: activatedcatalyst. Ethane Refrigerant (3 vol. ethane per vol. active feed)Staudinger 1 Percent Percent Ethyl a Mol.-\Veight' BF eth 'd Copolymers;having about 2% of combined styrene and 98% isobutylene, weremade-having two difierentaverage molecular weight ranges, one about12,000 and the other about 78,000.

These copolyiners were then blended in several concentrations upto.40%#by weight in a paraffin waxhaving a mf'eltingipoint of about KB:All

of" these" blends were completely homogeneous even at temperatures wellabove *the melting point of the wax, showing good solubility of thecopolymers of such low styrene content in molten paraffin wax. Therefractive index ot-each; of these blends was determined "at"60"[C"'and'the data'lwefe suitimar-izedias -follow Mbtwe reb dme Y Perzaen't'Copolymer in ex Mol. weight of polymeric product (Staudinger method)Percent Sample No.

The above data show that when 1% of styrene is copolymerized withisobutylene the molecular weight of the product is lowered about 40% butlarger amounts of styrene up to 4 or 4.5% only make relatively smallfurther reductions in the molecular weight of the resulting copolymers.On the other hand, the presence of the l to 4% or so of styrene in thecopolymer effects a great improvement in the stability of the copolymeragainst molecular weight breakdown when subjected either to mechanicalshear; elevated temperature or oxygen.

For instance, the following mill stability tests show that the abovedescribed copolymers having from 1 to 4.5% of combined styrene suffermuch lower breakdown in molecular weight than a polybutene made underthe same polymerization conditions. In this series of tests in which thepolymer was milled on a pair of steel rolls such as commonly used forhot milling rubber, the mill clearance used was 0.015 inch and the milltemperature was 305 F. Samples were taken every 10 mins. up to 1 hour.

Mm stability tests 1 P r e vi g provemen Percent styrene Percent Mol;gsgfigg g over polyin feed Wt. retained p polvbutene butene, for

- each 1% styrene in copolymer 1 These calculations on the relativeimprovements indicate that the greatest proportionate improvement isobtained with the first per cent of styrene, and that althoughsubsequent further additions of styrene in the polymerization feedeilect further improvements in the molecular weight retention duringmilling, such subsequent additions of styrene are relatively lesseffective when compared on the basis of the amount of styrene used. Itis also significant that as little as 4.5% of styrene in the feedproduces about 75% mol. wt. retention, so that obviously much largeramounts of styrene such as 20% or 50% could not possibly eifect a' muchgreater improvement in mol. wt. retentionthan is obtained with thisstill relatively minute amount of 4.5%.

EXAMPLE} Three tripolymers were made having low unsaturation and lowcombined cyclic constituent, by copolymerizing 95 or 96% of isobutylenewith 1 to 3% of styrene and 2 to 4% of isoprene, using 2 volumes ofmethyl chloride as solvent per volume of active feed, and using liquidethylene as internal refrigerant to maintain a polymerizationtemperature of about l03 C., and using as catalyst about by weight(based on the active feed) of a 0.4% solution of AlC13 in methylchloride. 1

The resulting tripolymers were tested for molecular weight and were thenvulcanized using the following curing formula and using a 20 min. cureat 307 F.:

MOLECULAR WEIGHTS AT DIFFERENT MILLING TIMES I Minutes Percent styreneinfeed The above data show that the plain poly- Parts by weight butenebroke down from a molecular weight of Tri 1 221,000 to about 25,000 andthus retained only ,3 15; a; 11.4% or the original molecular weight,whereas Zinc stearat "1 50 the copolymer with even as little as 1% ofstyrene Sulfur e i broke down from 138,000 to only 39, 0 therebyretaining 28.2% of its original molecular weight. Tetramethyl tmuramdlsulfide 1 Mercapto-benzothiazole 0.5

The composition of the copolymerization feed, molecular weight, andphysical tests on the cured products were as follows;

gene's-s9 3 Table vi copolymerization active feed:

styrene; l 2 isobutylene.- 95 96 95 isoprene 4 2 2 Total 100 100 cProduct:

moLwt. (Staudinger)- 44, 000 52. 000' 43,- 000 tensile (lbs/sq. in.);2,420 2.640 2, 100. modulus (at 300%) 250- 530 490 Percent elong. (tobreak). 910 875 I 900 mole percentunsaturation' 213%., H 1. -4 V l. 7

EXAMPLE-11'.

4.5% by weight of styrene .wa's' copolymeriz'ed with 95.5 %.'1of'isobutylene at. .1'01 3,"C.} using 2' volumes of methyl chloride assolvent per volume of active olefin feed, and. using. .as.,.cat'aly st.AlCl; in CHaCl solution- The yi'eldfof thecopolymer was 64% (dry weight)and its molecularflweight was 82,000 (by Staudinger method).Thiscopolymer had a Williams plasticityof' 207j and a recovery of 87. Italsohad a tensile strength of 58 lbs/sq. in. and-anelongation of 1725%.These characteristics indicate that this copolymer more nearly resemblesthe high molecular weight elastic or rubbery polybutenes (e. g. having amolecular weight of 150,000or'so) than the resinous or plasticstyrene-isobutylene" copolymers which contain 30. or 50%.1orso'ofstyrene, but compared to polybutene this copolymer containing 4.5% ofstyrene hasmuch better stability against mechanical breakdown-heatandsun: light.

. EXAMPLE- 12 4.0% by weight of'c methyl pemethyl styrene wascopolymerized with 98% of isobutylene at 101.3 C., using 2 volumes ofmethyl chloride as solvent per volume of active olefin feed and using ascatalyst-AlBra in CI-IaCl solution; (1 solution). The yield of thecopolymer was 49% (dry wt.) and its molecular weight was 69,000(Staudinger). This copolymer had a tensile of 50 lbs/sq. in. and anelongation of 1840%. The polymer was soluble in diisobutylene, benzene,and toluene.

EXAMPLE 13 2.0% by weight of a. methyl P'methyl styrene wascopolymerized with 95% of isobutylene and 3% of 2-3 dimethyl butadiene1-3 at 101.3 C., using 2 volumes of ethyl chloride as solvent per volumeof active olefin feed and using as catalyst T1014 in CHaCl. Theconcentration of TiCh in CHaCl was 2% by weight. About 20% by volume (toactive olefin) of cataly t solution was used. Yield of tripolymer (drywt.) was 82%. Staudinger mol. wt. of tripolymer was 38,000. Iodine No.of polymer was 3. The tripolymer was soluble in benzene, di-isobutylene,and toluene.

EXAMPLE 14 A mixture of 10% of mono-vinyl acetylene and 5% of styreneand 85% of isobutylene by weight is placed in a Dewar chamber which hasbeen fitted with an agitator. The mixture was cooled by adding somesolid carbon dioxide and then was blown with dry nitrogen as an internalrefrigerant till the mixture was cooled to about 100 C., and maintainedthus during the reaction. While stirring the reaction mixturevigorously, about 1% of boron trifluoride in the form of a solution of8% of boron trifluoride in methyl chloride was added at a rate of 20cc.per minute.

A vigorous-exothermic reaction-"took lacepro- V ducing a tacky solidwhich had a'-Staudi'nger mol. wt. of'about 38,000, and an iodine No. of,6.7, which indicated thatabout 8% mono-vinyl acetylene had combined intothe copolymer. The reaction was killed with alcohol andthepolymer waswashed" with water and dried. Yield of dry polymer was 83% by weight Thepolymer was compounded and vulcanizedusing the following formula:

Parts Polymer 100 Mercapto-benzothiazole -1 A Stearic acid 3 Zinc'dibutyl'dithiocarb'amate' 1 1 Zincoxide 10 Carbonblack 25 Sulfur 3 Thisstock upon heating lat-150 C. for 30 min. gives a product. which hasatensile strength of 1,800 lbs/sq. in. andan elongation of998% to break.

It is not intended that this inventionbe limited tothe specificmaterials:- which have been mentioned-merely for thesake of illustrationbut only by the appended claims-in which it is intended to claim allnovelty inherent in the-invention as well asall modifications comingwithin the scope and spirit of the invention.

We claim:

1..--l= 'rocess according; to claim 12'using- -90 to 98% ofisobutylene.1'to 5% of styrene and'about 0. 5 rto5 of isoprene.-

2..- Process according to claim 12- carried out at a temperature ofabout 103 C. using'liquid ethylene as refrigerant, and using as catalysta solution of aluminum chloride in methyl chloride, andthereaction-being carried out in the presence of about ZfVOIUmGS of;-methylchloride as inert solvent per volume of 'mixed reactants.

3.. The process-which comprises preparing a vulcanizable; rubberytripolymer-1 according to claim 12, and then curing the resultanttripolymer with a small amount of sulfur in the presence of avulcanization accelerator.

4. Product comprising essentially a vulcanizable rubbery tripolymer ofabout to 98% by weight of isobutylene, about 1 to 5% of styrene andabout 0.5 to 5% of isoprene, said tripolymer having an average molecularweight of at least 30,000 and having an I No. of about 0.5 to 20.

5. Product consisting essentially of a sulfurcured tripolymer of about90 to 98% by weight of isobutylene, about 1 to 5% of styrene and about0.5 to 5% of isoprene, said tripolymer having before curing an averagemolecular Weight of at least 30,000 and an I No. of about 0.5 to 20, andsaid cured tripolymer having a reduced I No. and a higher tensilestrength and modulus.

6. A vulcanized tripolymer of at least about 80% by weight ofisobutylene, about .01 to 5% of a styrene, and about 0.1 to 15% ofmono-vinyl acetylene.

'7. A product consisting essentially of a tripolymer of by weight ofisobutylene, 3% of styrene and 2% of 1,3-butadiene, said tripolymerhaving an average molecular weight of about 18,000 and being soluble inbenzene at 20 C., and having an iodine number of about 1.

8. The process of making high molecular weight copolymers having aniodine number of 0.1 to 50, and an average molecular weight of at leastabout 18,000, by the Staudinger method, which coman alkene having 3 to 8carbon atoms, about .01

the group consistingof a polyene of-to 15 carbon atoms and vinylacetylene, at atemperature below C. with a Friedel-Cra-fts catalyst.- ii 9. Product comprising essentially a high molecular weight tripolymerof at least 80% by weight of an alkene having 3 to 8 carbon atoms, about.01 to of a polymerizable monoolefinic hydrocarbon selected from thegroup consisting ofun alkylated aromatic hydrocarbons and derivativesthereof containingat least one alkyl group of 1 to 10 carbon atoms, andabout 0.1to-% of an unsaturated aliphatic selected from the groupconsisting of a polyene of 4 to 15 carbon atoms and vinyl acetylene,said tripolymer having an iodine number of about 0.1 to and an averagemolecular weight of at least about 18,000, by the Staudinger method.

10. A vulcanized tripolymer of at least by weight of an alkene having 3to 8 carbon atoms, about .01 to 5% of a polymerizable monoolefinichydrocarbon selected from the group consisting of unalkylated aromatichydrocarbons and derivatives thereof containing at least one alkyl groupof 1 to 10 carbon atoms, and about 0.1 to 15% of an unsaturatedaliphatic selected from the group consisting of a polyene of 1 to "15carbon atoms and vinyl acetylene, saidtripolymer having had beforevulcanization a molecular weight of at least about 18,000, by theStaudinger method.

11. A vulcanizedtripolymer of about to 98% by weight of isobutylene,about 0.5 to 5% of an aromatic hydrocarbon selected from the groupconsisting of polymerizabie monoolefinic aromatic hydrocarbons having 1to 2 rings, and derivatives thereof containing 1 to '2 methyl groups,and about 0.5 to 5% of a conjugated aliphatic diolefln 16 of 4 to 6carbon atoms, said tripolymer having had before vulcanization amolecular weight of at least about 18,000, by the Staudinger method.

12. The process of making high molecular weight rubbery copolymershaving an iodine number of not more than 20, an average molecular weightabout 30,000 and having substantially better stability againstdegradation by mechanical working, heat, light, and oxidation, than apolybutene of similar molecular weight, which comprises copolymerizingabout 80 to 99% by weight of isobutylene, about .01to 5% of styrene andabout 0.1 to 15% of an unsaturated aliphatic hydrocarbon selected fromthe group consisting of a polyene of 4 'toi 8' carbonatoms and vinylacetylene, in the presenceof 1 to 5 volumes of inertsolventeper volumeof mixed reactants, at a temperaturejbelow 50 0., in the presence of acatalyst selected from the group consisting of a Friedel-Craftscatalystdissolved in a lower alkyl halide of l'to 2. carbon atoms and aFriedel-Crafts catalyst promoted by a small amount of an ether,hydrolyzing; and removing the catalyst and evaporating thejsolvent.

WILLIAM J. SPARKS.

DAVID W. YOUNG.

7 QR FERENCES CITED The. following references are of record in the fileof this patent:

v UNITED STATES PATENTS Number Name Date 2,213,423 Wiezevich Sept. 3,1940 2,274,749 Smyers Mar. 3, 194 2,368,538 Gleason Jan. 30, 19452,373,706 Ott Apr. 17, 1945 2,446,536 Hardy Aug. 10, 1948 2,479,450Young Aug. 16, 1949 FOREIGN PATENTS Number 7 Country Date 513,521 GreatBritain Oct. 16, 1939

9. PRODUCT COMPRISING ESSENTIALLY A HIGH MOLECULAR WEIGHT TRIPOLYMER OFAT LEAST 80% BY WEIGHT OF AN ALKENE HAVING 3 TO 8 CARBON ATOMS, ABOUT.01 TO 5% OF A POLYMERIZABLE MONOOLEFINIC HYDROCARBON SELECTED FROM THEGROUP CONSISTING OF UNALKYLATED AROMATIC HYDROCARBONS AND DERIVATIVESTHEREOF CONTAINING AT LEAST ONE ALKYL GROUP OF 1 TO 10 CARBON ATOMS, ANDABOUT 0.1 TO 15% OF AN UNSATURATED ALIPHATIC SELECTED FROM THE GROUPCONSISTING OF A POLYENE OF 4 TO 15 CARBON ATOMS AND VINYL ACETYLENE,SAID TRIPOLYMER HAVING AN IODINE NUMBER OF ABOUT 0.1 TO 50 AND ANAVERAGE MOLECULAR WEIGHT OF AT LEAST ABOUT 18,000, BY THE STAUDINGERMETHOD.